Three questions arose recently: about Love, Money, Ideas, and How do we know if the universe is expanding.
I do not know if the universe is expanding as how could I. But I wondered how any one could assert that, as it was asserted, which was how the question came up.
On the outside of the universe it could be seen to expand, so to speak, but, then, it wouldn’t be the universe seen to expand but a part of it, the part seen to expand, as the outside would be a part of the universe but not under observation. How could it be seen to expand from the inside? What measure could / would be there to measure it against?
It was a problem of extrinsic and intrinsic geometry. It all started with the question: is the universe finite or infinite. I could only wonder how it could be known, one way or the other. I said that I wondered how a finite universe could be finite but without an end.
My answer, as I was pressed to give one, was theological.
I said it was the similar to the question as to how anyone could know if god was infinite: a theological conundrum: regarding god and the universe as a unity. There actually historically was an answer figured out theologically but it was to the satisfaction of only a few. If the universe was infinite then it would be commensurable as an infinite thing would be known to have a number however infinite it might be. Since god was not considered commensurable then god could not be infinite. Anything finite was by definition commensurable so then an incommensurable god could not be finite.
Anything to be measured or assigned a number would have to be so described by human standards and could be known. Anything in the universe was actionable upon if it was known. Anything knowable must be subject to measure and must be subject to number and must be subject to action upon it. Anything acted upon was therefore subject to change. No action upon god was considered possible. “Obviously”, no one was considered able to change god.
If the universe was a one then it was indivisible infinitely and numbered and thus god could not be a one. If the universe was a many then it was enumerable and thusly numbered and thus god could not be a many.
Therefore god was beyond mortal measure. Harrumph!
What could be known of god? The honest theologians replied that nothing was knowable about god, it was believed or not, that god was an organizing principal for humanity, and humanity was forever organizing and reorganizing and thereby changing the belief in god but not losing the absolute necessity for organizing principals. They continued that the questions about life and existence started with beliefs and developed into knowledge which was the endless task for humanity and would take forever, and that we need to keep faith in goodness and justice and togetherness (… and so on …) within such eternally continually developed reason. Amen.
The universe was only knowable over time and thus only finite within the limits of our knowledge. The universe was assumed infinite as there was no known end to time nor space nor anything else needed to get to know it. If we ever found an end to the unknown then our questions would be answered. Until then, the universe would be knowable finitely at any time.
However, the issue of an infinite versus finite universe was a false issue as it assumed one or the other without evidence for either, except as argued above and before. There was no measure possible for a universe we have not completed measuring to conclusively figure outside of belief that there was an infinite universe.
And thusly I completed my answer.